Widely used measure to offset CO2 emissions can disrupt natural ecosystems, says report
Popular measures to combat climate change such as tree planting and switching to bioenergy can harm nature and undermine efforts to reduce global warming, according to a report by 50 leading scientists. Some strategies that focus on reducing greenhouse gas emissions damage wildlife and natural habitats and must be assessed in a more holistic way, said researchers from the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.
“Biodiversity loss and climate change are both driven by human economic activities and mutually reinforce each other,” the researchers said. “Neither will be successfully resolved unless both are tackled together.” The recent focus by companies and governments on planting trees to help absorb carbon is not a cure-all, the scientists warned. The right trees must be planted in the right places in order not to destroy local ecosystems, said the report, adding that climate change can “drastically reduce the mitigation potential of forests, due to an increase in extreme events like fires, insects and pathogens”.
Hans-Otto Pörtner, co-chair of the workshop that produced the report, said relying on natural solutions to warming was “a vision that may not come true if we let climate change go on . . . even large ecosystems like the Amazon rainforest are progressively losing their ability to support mitigation”. The priority, he added, must be working to reduce global emissions. Attention has turned towards so-called nature-based solutions to cutting emissions as national targets to reach net zero become more ambitious and organisations seek affordable ways to reduce their carbon footprint.
Planting trees — which can generate the carbon offsets organisations use to compensate for polluting — is a growing area of focus and attracts investors hoping to develop new revenue streams. Meanwhile, a crisis in biodiversity is rising up the political agenda. The G7 has pledged to protect at least 30 per cent of the world’s land and oceans, and promised this month to “embed” biodiversity loss considerations into economic and financial decision-making. Yet the two strands of climate and nature are often not considered together — with potentially dangerous consequences, the scientists said.
Planting single species crops that are used as the fuel for bioenergy — renewable energy that produces heat and power — is “detrimental to ecosystems when deployed at very large scales,” the researchers said. Yet bioenergy as a replacement for fossil fuels is being written into emissions reduction blueprints by groups including the influential International Energy Agency and the UK’s Climate Change Committee, which advises policymakers. The scientists called on governments to end subsidies for activities that harmed nature, such as deforestation and overfishing, and said “clear accounting standards” for carbon offsets — which vary in quality and legitimacy — should be agreed at an international level.